Palletizing machines are well known for automated placement of boxes in layers upon pallets for movement of the boxes from manufacturing plants to distribution and sales locations. Typically an automatic box feeder, such as a belt conveyor or gravity roller apparatus will feed a sequence of boxes into a palletizing machine, and the machine will then position rows of boxes into layers, and then position additional boxes into more layers stacked upon each other. The pallet with the stacked layers of boxes will then be moved by a fork truck to a storage or transport location, as is well known.
Efforts persist to improve palletizing machines to thereby minimize the cost of materials and manufacture for such machines, and to minimize labor costs to build and operate such machines. For example, in U.S. Pat. No. 4,614,473 to Kwauka et al., a palletizing machine is disclosed that includes a pusher bar for pushing rectangular objects, such as books or boxes, onto a pallet. The pusher bar is retracted from a position over the pallet back to a start position by complex piston cylinder units that raise the pusher or sweep bar over incoming books that are next pushed by the sweep bar. Similarly, in U.S. Pat. No. 4,711,612 to Kwauka, a retracting pusher bar is raised during retraction by a complex piston assembly. In U.S. Pat. No. 5,733,100 that issued to Slat et al., a pusher bar of a palletizing machine for cylindrical objects is disclosed as being raised during re-positioning by a cylindrical piston. In U.S. Pat. No. 5,472,077 to Bolin, shows retraction of a pusher arm in a raised position through use of a controller and electric motors. These Patents also disclose many complicated and unique components of each machine that are necessary for the palletizing machines to operate efficiently.
As is apparent, use of hydraulic cylinder and piston apparatus or electric motor assemblies are common in such extraordinarily complex palletizing machines. Many of the known palletizing machines are specifically designed only for limited sized of objects being palletized. While such complex machines serve to minimize labor costs, they are nonetheless very costly to manufacture and operate. Accordingly, there is a need for a palletizing machine that minimizes cost of manufacture and operation.
(Most palletizing machines position “boxes” upon pallets, meaning rectangular, cardboard objects that contain an article of manufacture. However, in some instances, palletizing machines may also position articles of manufacture that are not contained within “boxes”. Therefore, for purposes herein, it is to be understood that the word “object” or “objects” is to mean both a rectangular box or boxes, and any other articles of manufacture that are to be positioned upon a pallet.)